The Role of Diet in Managing Chronic Diseases

Introduction

Chronic diseases, such as obesity, type-2 diabetes, cancer, stroke, and heart disease, are leading causes of morbidity and mortality worldwide. Here are some statistics to highlight the extent of the problem:

• According to the Nuffield Trust, more than 15 million people have a long-term condition in England alone.
• In 2021, 26% of adults in England were obese (NHS England Digital), which can increase the risk of health problems and other diseases.
• 100,000 people have strokes each year, and there are 1.3 million stroke survivors in the UK (Stroke Association).
• According to the British Heart Foundation (BHF), 7.6 million people are living with heart and circulatory diseases and every 3 minutes someone dies.
• There are 4.3 million people in the UK living with diabetes, and 90% have type-2 diabetes (Diabetes UK).
• In 2023, an estimated 3 million people were living with cancer in the UK, and each year, around 167,000 people die from the disease (Macmillan Cancer Support).

Some chronic diseases are preventable, but an increase in unhealthy lifestyles, such as poor diets, a lack of physical activity, smoking and excessive alcohol consumption, means that more people are being diagnosed with major illnesses. While medical interventions have a crucial role in managing these conditions, diet has a significant influence. It also has an essential role in disease prevention and physical and mental health and well-being promotion.

In this blog post, we will explore the powerful impact of dietary choices in preventing and managing chronic diseases.

Understanding Chronic Diseases

Chronic diseases are long-term conditions usually occurring for at least one or more years that often require ongoing management and treatment. Common examples include obesity, type-2 diabetes, certain cancers, stroke and cardiovascular disease.

Obesity

Consuming excess calories, especially those high in fat and sugar, and a lack of exercise can lead to obesity, which means having excess body fat. A person is classed as obese if they have a body mass index (BMI) of 30 or above. Those with a BMI of 25 to 29.9 are in the overweight range. According to the NHS, around one in every four adults and one in every five children aged 10 to 11 are living with obesity in the UK.

Obesity can lead to other health conditions, such as:

• Type-2 diabetes.
• Coronary heart disease.
• Certain cancers, e.g. bowel and breast.
• Stroke.
• Mental health problems, such as depression.

Type-2 diabetes

Type-2 diabetes is caused by a person’s blood sugar (glucose) being too high due to a lack of the hormone insulin. It usually correlates with obesity, being overweight or inactive, or a family history of this condition. More than 2.4 million people are at an increased risk of type-2 diabetes in the UK based on blood sugar levels (Diabetes UK).

It is a long-term condition that can significantly affect a person’s life and may require them to take medicines and change their diet. It can also cause serious health problems if blood sugar levels are high, such as strokes, heart attacks and kidney, feet or eye issues.

Certain cancers

Poor nutrition and being overweight or obese can lead to certain cancers, which is where cells in a particular part of the body grow and reproduce uncontrollably. The cancerous cells invade and destroy healthy tissue and organs (NHS). According to Macmillan Cancer Support, up to one-third of cancers (30%) in the UK could be preventable by healthier diets. Cancer Research UK has information on how obesity causes cancer here.

Cancer can significantly impact those diagnosed and their families and friends. Those with cancer can experience unpleasant symptoms, and although there are treatments available, a healthy lifestyle is essential in preventing and managing the disease.

Stroke

A stroke occurs due to a cut off of the blood supply to part of the brain because of high blood pressure or a blood clot. Strokes can be caused by being overweight or obese, a lack of exercise, increased blood pressure and high cholesterol levels. Overweight people showed a 22% greater probability of ischaemic stroke, and obese people had a 64% increased probability compared to normal-weight subjects (the Brain Injury Association).

Stroke affects people differently. Some may have minor and short-lived effects; others can experience serious long-term health problems. The Stroke Association has further information on the effects here.

Cardiovascular disease

Poor nutrition can increase the risk of many heart conditions, e.g. coronary heart disease, where a build-up of fatty substances can block or interrupt blood supply to the heart. An unhealthy diet, poor lifestyle, being overweight, and obesity can increase blood pressure and cholesterol, which can lead to heart disease and increase the risk of angina, heart attacks and heart failure.

It can be hard after a diagnosis of heart disease and can involve treatment and rehabilitation. NHS Inform has further information on this here.

Factors influencing chronic diseases

A combination of various factors influence chronic diseases, including the following:

Genetics – a person’s genetics can predispose them to certain chronic diseases, especially those that are hereditary, e.g. heart disease, diabetes, Alzheimer’s and specific cancers.

Lifestyle choices – how a person lives and behaves can positively or negatively affect their health. Poor lifestyle choices can increase the risk of developing chronic diseases, for example:

• Smoking– the use of tobacco is a major risk factor for various cancers, stroke and heart disease.
• Physical inactivity– a lack of exercise can lead to obesity, heart disease and stroke.
• Poor nutrition – malnutrition can lead to people not getting enough nutrients or too many, which can cause obesity, diabetes, and cardiovascular issues. Foods high in salt, sugar and fat can increase the risks.
• Alcohol overuse– excessive consumption of alcohol can result in poor mental health, liver disease, heart disease and certain cancers.

Environmental factors – the environment to which a person is exposed can influence the development of chronic diseases, e.g., exposure to air pollution can result in chronic heart and respiratory diseases.

Social and economic factors – affect people’s health, choices, finances and abilities and can increase the risk of chronic diseases, e.g., a lack of financial resources, social isolation and disparities in healthcare access can impact health outcomes.

One of the major factors influencing chronic diseases is diet. According to Navratilova, et al 2024, “diet is a modifiable risk factor that has been shown to have a significant impact on the prevention and management of chronic diseases”.

The Link Between Diet and Chronic Diseases

Diet plays a pivotal role in chronic disease prevention, development and progression. Poor dietary habits, such as too much sugar, salt, and unhealthy fat, can increase the risk of certain diseases like obesity, type-2 diabetes, and heart disease (National Institutes of Health). In fact, a poor diet is now the biggest risk factor for preventable ill health in England, narrowly ahead of smoking (Health Foundation). Conversely, a healthy, balanced diet, i.e. rich in fruits, vegetables, whole grains, nuts and seeds, omega-3 fatty acids, low-fat dairy and lean proteins, can help prevent and manage chronic diseases.

Here are some examples of how diet and chronic diseases are linked:

• Too much sugar can increase the risk of developing type-2 diabetes and heart disease.
• Excessive consumption of salt can cause high blood pressure, which can increase the risk of stroke and heart disease.
• Too much fat, especially unhealthy saturated and trans fats, can raise cholesterol levels and increase the risk of heart disease.
• Consuming too much sugar, salt, unhealthy fat, processed meats, and excessive alcohol can increase the risk of developing certain cancers and heart disease.
• A lack of calcium and vitamin D in the diet and drinking alcohol excessively can lead to osteoporosis or arthritis.
• Sugar, fried foods, overcooked meat, excessive alcohol and refined carbohydrates can increase inflammation levels, which is common in chronic disease.
• Consuming too many calories, especially fats and sugar, can lead to obesity and associated chronic diseases, e.g. type-2 diabetes, heart disease, and certain cancers.

A diet that includes foods in the right balance and a variety of nutrients can significantly impact the risk of someone developing a chronic disease (Tucker, 2020). In some cases, dietary changes can actually result in someone with a chronic disease going into remission, e.g. according to Diabetes UK, there is strong evidence that type-2 diabetes is mainly put into remission by weight loss.

Key Nutrients for Managing Chronic Diseases

Humans need nutrients to live, grow and stay healthy. They must have a healthy and balanced diet to provide the nutrients they need to maintain bodily functions. If their diet is unhealthy and does not include the correct nutrients, it can lead to malnutrition, development issues, ill health and disease.

People need certain amounts of specific nutrients, known as the nutrient requirement, divided into macronutrients and micronutrients.

Macronutrients

People must consume these nutrients in large amounts, as they provide energy in calories and maintain body functions. Macronutrients are:

• Carbohydrates – provide most of the energy people require, which includes energy for the basic actions to sustain life (called the Basal Metabolic Rate).
• Fats – provide energy and warmth and help absorb specific vitamins, e.g. A, D, E and K.
• Proteins – repair and replace the body’s cells and tissues and are needed for growth.

Micronutrients

People need these nutrients in smaller quantities. However, they are still essential for human health. Examples include:

• Vitamins – support various functions, such as maintaining an effective immune system, blood clotting and absorption of foods.
• Minerals – are inorganic substances, e.g. iron and calcium, that the body cannot make but are important for various bodily processes.

Certain key nutrients have shown to have specific benefits in managing chronic diseases, for example:

Fibre

• It helps regulate blood sugar and cholesterol levels and promotes digestive and bowel health. It also helps with weight management.
• It is in fruits, vegetables, whole grains, starchy foods (potatoes with skins on), legumes (peas, beans, lentils, chickpeas and peanuts) and seeds.

Omega-3 fatty acids

• These have anti-inflammatory properties and support heart health.
• They are in fatty fish, flaxseeds, chia seeds, green leafy vegetables, and walnuts.

Antioxidants

• These protect cells from damage caused by free radicals and may reduce the risk of cancer and heart disease as they combat inflammation and oxidative stress.
• These are in various coloured fruits/vegetables, nuts, seeds, herbs, and spices.

Potassium

• It helps lower blood pressure and supports heart health.
• It is in bananas, leafy greens (e.g. spinach), potatoes, legumes, and avocados.

Magnesium

• It is important for regulating blood sugar levels and blood pressure.
• It is in nuts, seeds, whole grains, and leafy greens.

Calcium and vitamin D

• These are crucial for bone health. Vitamin D is necessary for calcium absorption.
• They are in leafy greens, dairy products, plant-based milk, fatty fish and fortified foods. Vitamin D is also obtainable from sunlight.

The Mediterranean Diet

The Mediterranean diet (MedDiet) is defined by BBC Food as:

“A set of loose principles that represent the traditional diet and lifestyle of those who live around the Mediterranean, in the countries of Greece, France and Italy.”

This diet is often hailed as one of the healthiest dietary patterns for preventing and managing chronic diseases and has many benefits, including:

• Weight loss – the diet tends to be lower calorie and high in fibre, so people feel fuller for longer, which can help them lose weight and reduce the risk of obesity.
• Reduces the risk of heart disease and stroke – the diet contains healthier fats and replaces saturated and trans fats. It also reduces salt, which can help with high blood pressure.
• Prevents type-2 diabetes – it minimises processed foods and reduces sugar, which can help lower blood glucose levels. It is also beneficial for those with type-1 diabetes to help manage their condition.
• Improved gut health – as the diet is higher in fibre, it can increase the amount of ‘good’ bacteria in our gut.
• Lowers cancer risk – the diet is low in red meat, saturated fat and sugar, which can reduce the risk of certain cancers, such as bowel, stomach, breast, bladder, lung, etc.
• Better brain function – as the diet contains more fish, less red meat and healthier oils, it can help improve brain health.

Studies have shown that following a MedDiet can reduce the risk of heart disease, stroke, and type-2 diabetes. Here are some examples of these studies (this list is not exhaustive):

• Adherence to a Mediterranean-Style Diet and Effects on Cognition in Adults: A Qualitative Evaluation and Systematic Review of Longitudinal and Prospective Trials – the review found that higher adherence to a MedDiet is associated with slower rates of cognitive decline, reduced conversion to Alzheimer’s disease, and improvements in cognitive function.
• Association between a Mediterranean lifestyle and Type 2 diabetes incidence: a prospective UK biobank study – the study concluded that higher adherence to the MEDLIFE index was associated with lower risk of type-2 diabetes in the UK Biobank.
• Diet and stroke: recent evidence supporting a Mediterranean style diet and food in the primary prevention of stroke – the review concluded there is evidence supporting an association between the Mediterranean diet pattern (both individual foods and full pattern) and decreased stroke risk.
• Mediterranean diet and health: A systematic review of epidemiological studies and intervention trials – the review concluded that the MedDiet has a favourable impact on health.

So, what is the MedDiet? It is a diet emphasising whole foods such as fruits, vegetables, nuts, seeds, whole grains, fish, and olive oil while limiting processed foods, red meat, and sugary beverages. Here is some guidance on how to follow the diet:

• Include a variety of vegetables, fruits, nuts, seeds, legumes, and whole grains.
• Choose healthy whole grains, e.g. quinoa, brown rice, oats, wholewheat pasta and wholemeal bread.
• Swap unhealthy fats, such as ghee, palm and animal-based, for healthy ones, such as olive oil.
• Include unsalted nuts and seeds, such as sunflower, pumpkin, sesame and poppy seeds, peanuts, walnuts, cashew nuts, etc.
• Consume fish at least twice a week, particularly oily fish such as mackerel, salmon and sardines.
• Reduce alcohol intake, and if drinking alcohol, limit it to a small glass of red wine a day, preferably with a meal.
• Limit red meat and replace it with lean meats (poultry) or plant-based protein sources where possible.
• Rather than use excessive salt, use herbs and spices to flavour meals.
• Limit dairy intake, but include low-fat and low-sugar options, such as plain Greek yoghurt and lower-fat cheeses, e.g. from goat or sheep milk.
• Choose whole foods and those that are minimally processed.

Further information

• BBC Food – What is the Mediterranean diet?
• British Heart Foundation – What is the Mediterranean diet?
• Guts UK Charity – The Mediterranean Diet & Gut Health.
• Heart UK – The Mediterranean diet.
• Netdoctor – Mediterranean diet: food list, benefits and 7-day meal plan.

Practical Tips for a Healthy Diet

A healthy and balanced diet includes a wide range of foods and drinks in the right proportions and amounts (NHS). Eating a healthy and balanced diet will help maintain a healthy weight and reduce the risk of chronic disease.

Here are some practical tips for a healthy diet:

Fruit and vegetables

• Aim for at least five portions of fruit and vegetables daily, which can be tinned, dried, frozen or fresh. Add it to your breakfast cereal or have it as a snack. One portion includes one apple, one banana, three heaped tablespoons of vegetables, etc.
• Enjoy various fruits and vegetables; the more colours and types, the better.

Wholegrains and starchy foods

• Include higher fibre starchy foods like potatoes, bread, rice, pasta, and cereals.
• Keep the skins on potatoes, as they are high in fibre.
• Choose whole grains over refined grains, e.g. wholemeal bread, wholewheat pasta and brown rice.
• Be aware of adding fats, such as butter and oil, to starchy foods, i.e. try not to add lots of butter to a jacket potato.

Meat, fish and plant-based

• Reduce the amount of red meat and opt for lean proteins such as poultry, fish, beans, eggs and legumes.
• Eat fish at least twice a week and one portion of oily fish high in omega-3 fatty acids. Be mindful of smoked and tinned fish, as they often contain more salt.
• Substitute meat in meals for other protein sources, e.g. plant-based alternatives, a few times a week.
• Limit processed meats, such as bacon, and choose leaner cuts.
• Trim the fat off the meat and grill instead of frying it.

Drinks

• Stay hydrated by drinking plenty of water throughout the day. Aim for 6-8 glasses, including water, lower-fat milk, sugar-free drinks and herbal teas. You can include tea and coffee, but be mindful of the caffeine.
• Use the colour of your urine as a guide. NHS Inform has a handy colour chart here.
• Limit fruit juices and smoothies to no more than 150ml daily, even though they count towards your five a day, as they contain a lot of sugar.
• Swap sugary soft drinks for diet, sugar-free or no added sugar varieties.
• Reduce alcohol intake and keep within the recommended units, e.g. 14 a week. The NHS has alcohol advice here.

Fats and dairy

• Replace saturated fats and trans-fats with unsaturated fats where possible, but eat them in small amounts.
• Cook with healthier oils such as olive, avocado, rapeseed and sunflower.
• Include some dairy or dairy alternatives (such as soya drinks).
• Choose low-fat dairy products and alternatives instead of high-fat ones.

Processed foods, salt and sugar

• Limit intake of processed foods, sugary snacks, and beverages high in added sugars and also those containing high salt content.
• Avoid ultra-processed foods (UPFs) by checking the ingredients for emulsifiers, colourings, sweeteners or preservatives.

Calories and diets

• Be mindful of calories, portions and the recommended intakes (2000 for women and 2500 for men). The NHS has further information on this here.
• Avoid extreme diets and get a balance between the different food groups.
• Try not to be too strict, as it is hard to sustain long-term and can lead to nutrient deficiencies.
• Choose various foods from the five main food groups.
• Practice portion control to maintain a healthy weight.
• Use the Eatwell Guide for guidance on achieving a healthy and balanced diet.

These tips are for adults with no specific dietary requirements or medical conditions. You should seek advice from your GP or dietician if you have particular needs or conditions.

Further information

• British Heart Foundation – Healthy eating – reduce your risk of developing heart disease.
• British Nutritional Foundation – A healthy balanced diet.
• British Nutritional Foundation – Health conditions.
• Cancer Research UK – Diet and cancer.
• CPD Online – Importance of Healthy Eating.
• Diabetes UK – What is a healthy, balanced diet for diabetes?
• NHS – Eating a balanced diet.
• Stroke Association – Eat a healthy diet.
• The Association of British Dietitians – Heart Health.

Conclusion

Our diets are getting poorer, and our consumption of ultra-processed foods, sugar, fat and salt is increasing. As a result, more people are developing chronic diseases, such as obesity, type-2 diabetes, heart disease, cancer and many others. These diseases can significantly impact those diagnosed and their family and friends. They can also burden health and social care systems and significantly cost the taxpayer.

Many factors can influence the development of chronic diseases, such as genetic, lifestyle, environmental and social. However, the role of diet in preventing and managing chronic diseases cannot be overstated. By making informed dietary choices and adopting a healthy, balanced diet and lifestyle, individuals can significantly reduce their risk of developing chronic conditions and better manage existing ones.

There has been a lot of research on diets, and the Mediterranean diet is believed to have many health benefits and can reduce the risk of chronic diseases. Whether you choose to follow a specific diet, such as the Mediterranean diet, or start cutting down, it is important to remember that even small changes to your diet can lead to significant health and well-being improvements in the long run.